The Necromancer Class card (from the Pathfinder expansion) has a class ability that allows them to discard three cards from their hand to take the first monster in the discards pile and add it to combat (adding the Undead subtype).

The question that is/was being disputed in our game is whether the Necromancer's ability can be used only during your own turn, or during any combat.

The argument for the "only on your turn" interpretation: The exact phrasing used on the card is not "during any combat" as it is on so many other cards, and is instead "during combat" (without the any). If it was meant to allow use during any combat, it would have said so.

The argument for the "during any combat" interpretation: The exact phrasing used on the card is not "during combat on your turn" (or some equivalent statement), but "during combat". If it was meant to be more restrictive, it would have said so.